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    <td width="100%"><font face="Verdana" size="2"><i>&nbsp;UDT Reference: UDT 
	Functions</i></font></td>
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<h1 style="margin-bottom: 0"><font face="Verdana" size="4">recv</font></h1>
<p><font face="Verdana" size="2">The <b>recv </b>method receives certain size of 
data into a local memory buffer.</font></p>
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    <p style="margin-top: 0; margin-bottom: 0">
    <font size="1" face="Courier New">int recv(<br>
&nbsp; UDTSOCKET <font color="#FFFFFF">u</font>,</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font size="1" face="Courier New">&nbsp; char *<font color="#FFFFFF"><a class="synParam" onclick="showTip(this)">buf</a></font>,</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font size="1" face="Courier New">&nbsp; int <font color="#FFFFFF"> <a class="synParam" onclick="showTip(this)">len</a></font>,</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font size="1" face="Courier New">&nbsp; int <a class="synParam" onclick="showTip(this)"><font color="#FFFFFF">flags</font>,</a></font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font face="Courier New" size="1">&nbsp; int *<font color="#FFFFFF">handle </font>
	= NULL,</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font face="Courier New" size="1">&nbsp; <a href="structure.htm#MEM">UDT_MEM_ROUTINE</a>
	<font color="#FFFFFF">routine</font>&nbsp;= NULL,</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font face="Courier New" size="1">&nbsp; void* <font color="#FFFFFF">context
    </font>
	= NULL</font></p>
	<p style="margin-top: 0; margin-bottom: 0">
    <font face="Courier New" size="1">);</font></p>
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<h4><font face="Verdana" size="2">Parameters</font></h4>
<dl>
	<dt><font face="Verdana"><i><font size="2">u</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[in] Descriptor identifying a connected 
	socket. </font></dd>
	<dt><font face="Verdana"><i><font size="2">buf</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[out] Buffer used to store the incoming 
	data. </font></dd>
	<dt><font face="Verdana"><i><font size="2">len</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[in] Expected length of the data to be 
	received. </font>
	</dd>
	<dt><font face="Verdana"><i><font size="2">flags</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[in] Ignored. For compatibility use only.</font></dd>
	<dt><font face="Verdana"><i><font size="2">handle</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[out] Optional. An descriptor to this <b>recv</b> call.</font></dd>
	<dt><font face="Verdana"><i><font size="2">routine</font></i><font size="2">
	</font></font> </dt>
	<dd><font face="Verdana" size="2">[in] Optional. Function used to process the buffer (received data)
	after the receiving is finished. </font></dd>
	<dt><font size="2" face="Verdana"><i>context</i></font> </dt>
	<dd><font face="Verdana" size="2">[in] Optional. Context parameter used in
      the buffer process routine. </font></dd>
</dl>
<h4><font face="Verdana" size="2">Return Values</font></h4>
<p><font face="Verdana" size="2">On success, the actual size of received data is returned; Otherwise,
UDT::ERROR 
is returned and the specific error information can be retrieved by 
<a href="error.htm">getlasterror</a>. If UDT_RCVTIMEO is set to a positive
value, zero will be returned if no data is received before the timer expires.</font></p>
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      <th align="center" bgcolor="#C0C0C0" width="133">
		<font face="Verdana" size="2">Error Code</font></th>
      <th align="center" bgcolor="#C0C0C0" width="812"><b>
      <font face="Verdana" size="2">Comment</font></b></th>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		2001</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		connection broken before send is completed.</font></td>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		2002</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		<i>u 
		</i>is not connected.</font></td>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		5004</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		<i>u 
		</i>is an invalid UDT socket.</font></td>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		5010</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		cannot use <i>recv</i> in SOCK_DGRAM mode.</font></td>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		6002</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
		no data is available to be received on a non-blocking socket.</font></td>
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      <td width="133">
      <font face="Verdana" size="1">6003</font></td>
      <td width="812">
      <font face="Verdana" size="1">no buffer available for the non-blocking
      recv call.</font></td>
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      <td width="133">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">6004</font></td>
      <td width="812">
      <p style="margin-top: 1; margin-bottom: 1"><font face="Verdana" size="1">
        an overlapped recv is in progress.</font></td>
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<H4><font face="Verdana" size="2">Description</font></H4>
<P><font face="Verdana" size="2">The <b>recv </b>method reads certain amount of 
data from the protocol buffer. If there is not enough data in the buffer, <b>recv</b> 
only reads the available data in the protocol buffer and returns. On 
non-blocking socket, <b>recv</b> returns immediately, otherwise <b>recv</b> may wait until 
some data is available to read.</font></P>
<P><font face="Verdana" size="2">If the <i>handle</i> parameter is assigned, the <b>recv</b> 
method is enabled with overlapped IO processing. On blocking mode, UDT will wait 
until exact the same size of <i>len</i> data are received. On non-blocking mode, 
<b>recv</b> 
returns immediately but the successive data continue to be written into the user 
buffer. In either case, after the IO is completed, the function pointed by 
<i>routine</i> (if it is not NULL) will be called to process the buffer. Note
that UDT does not duplicate the <i>context</i> parameter: it should remain valid
until the <i>routine</i> is called, and it should be released (if necessary) by
applications. The progress
the overlapped <b>recv</b> can be queried by using <a href="overlap.htm">getoverlappedresult</a>.</font></P>
<P><font face="Verdana" size="2">Non-blocking overlapped receiving is exclusive.
If there is at least one non-blocking overlapped call in progress, all further
regular <b>recv</b> (non overlapped), <a href="recvfile.htm">recvfile</a>, and
blocking overlapped <b>recv</b> will be rejected with error number 6004. This is
due to an implementation limitation.<br>
<br>
Note that, <a href="opt.htm">UDT_RCVTIMEO</a>
does NOT apply to overlapped <b>recv</b>.</font></P>
<H4><font face="Verdana" size="2">See Also</font></H4>
<P><b><font face="Verdana" size="2"><a href="select.htm">select</a></font></b><font face="Verdana" size="2"><b>, 
<a href="send.htm">send</a>, <a href="sendfile.htm">sendfile</a>, <a href="recvfile.htm">recvfile</a>,
</b><a href="overlap.htm"><b>getoverlappedresult</b></a></font></P>

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